Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/0009—Pigments for ceramics
  • C09C1/0012—Pigments for ceramics containing zirconium and silicon
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/08—Intercalated structures, i.e. with atoms or molecules intercalated in their structure
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
  • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
  • C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/12—Surface area

Definitions

• the present invention relates to grayish-black encapsulated pigments based on zirconium silicate as the casing substance into which colored compounds are encased as a discrete phase.
• the present invention also relates to a method of producing these encapsulated pigments.
• Encapsulated pigments or inclusion pigments have become known, in the prior art as, for example, from DE-PS 23 12 535. They consist essentially of transparent crystals of glaze-stable substances such as e.g. zirconium silicate, zirconium oxide or tin oxide into which inorganic, moisture-free, colored compounds are included or encapsulated as a discrete phase. Thenard's blue (cobalt blue), titanium yellow and especially cadmium yellow and cadmium red are examples of colored compounds. Zirconium iron rose with Fe 2 O 3 inclusions in a zirconium silicate casing is also known.
• Gray and black bodies are obtained essentially from iron oxides and chromium oxides, optionally in combination with other oxides such as e.g. manganese oxide, copper oxide, nickel oxide or cobalt oxide. Grayish-black encapsulated pigments were not known in the past.
• An object of the present invention therefore is to provide grayish-black encapsulated pigments consisting essentially of colorless crystals of zirconium silicate in which colored compounds are encapsulated as a discrete phase. Another object is to provide a method of producing these encapsulated pigments with which a relatively high yield can be achieved.
• a feature of the invention whereby the above and other objects are obtained resides in carbon black particles with specific surface areas (according to BET) of 10 to 1000 m 2 /g, preferably 30 to 120 m 2 /g, which are encased as the colored compounds.
• the carbon blacks can be of differing origin, such as e.g. so-called gas blacks, furnace blacks or lampblacks.
• These pigments exhibit a gray to black color and different color nuances or shades can be the result of varying amounts as well as varying origin and particle sizes of the encapsulated carbon black particles.
• the new grayish-black encapsulated pigments can be obtained by grinding and subsequently calcining a mixture of silicon dioxide, zirconium oxide, and the colored compound to be encapsulated along with conventional mineralizers at 900° to 1400° C.
• the method of the invention is characterized in that zirconium oxide is used with a particle size distribution (D50 value) of 7 to 10 ⁇ m and a specific surface area (geometrically determined) between 2 and 4 m 2 /g.
• the colored compound to be encapsulated carbon black is used with a specific surface area (according to BET) of 10 to 1000 m 2 /g in an amount up to 50% by weight relative to zirconium silicate obtainable from the SiO 2 and ZrO 2 present.
• the resulting ground mixture is heated first under reducing conditions to 900° to 1400° C., calcined there for 0.5 to 8 hours and then calcined at 900° to 1400° C. under oxidizing conditions for removal of the non-encapsulated portion of carbon black.
• carbon blacks are used with specific surface areas between 30 and 120 m 2 /g, determined according to the BET method using nitrogen (DIN 66131). They are conventional carbon blacks like those obtainable commercially as coloring or inking blacks or rubber blacks. Such carbon blacks generally exhibit an average primary particle size according to DIN 53206 in a range of approximately 10 to 100 nm. The carbon blacks are preferably added in amounts of 20 to 25% by weight based on the amount of zirconium silicate. The agglomerate size (determined by granulometry in water) of the carbon black particles used by way of example was between 1 and 15 ⁇ m; this size range is not essential for the invention. The specific surface area of the zirconium oxides to be used was determined geometrically from the particle size distribution.
• the heating rate is preferably between 800° and 1000° C./hour; however, heating rates of e.g. 200° to 800° C./hour were also successful.
• the optimum heating rate also depends partially on the calcining furnace available. A calcination temperature between 1000° and 1300° C. is preferred.
• Customary mineralizers as are well known in the art can be used such as alkali metal halogenides or alkaline earth metal halogenides, preferably alkali metal fluorides and alkaline earth metal fluorides, especially magnesium fluoride, and alkali metal silicofluorides.
• alkali metal halogenides or alkaline earth metal halogenides preferably alkali metal fluorides and alkaline earth metal fluorides, especially magnesium fluoride, and alkali metal silicofluorides.
• One or more of such mineralizers can be used.
• Zirconium oxide and silicon dioxide are used in essentially equivalent amounts.
• the mixture to be calcined is ground prior to the calcining process, e.g. in a ball mill or in other intensive grinding mills.
• the calcination can take place in conventional furnaces such as e.g. in piston furnaces (furnace for getting the product to be calcined heated up within the shortest time), chamber furnaces or tunnel furnaces. Furnace conditions as well as compressing conditions are well known. At a calcining temperature of 1000° C., a dwell time of one hour is usually sufficient. Gray to black products are obtained in this manner with a yield of approximately 80% relative to the theoretically possible formation of ZrSiO 4 .
• an oxidizing recalcination is carried out.
• the oxidizing calcination takes place at 900° to 1400° C. whereby a calcining time of 0.5 to 1 hour is generally sufficient at 1000° C.
• the encapsulated pigments produced in accordance with the invention contain more than 0 and less than 0.5% by weight carbon black included.
• a furnace black with a specific surface area of approximately 60 m 2 /g, primary particle size approximately 40 nm, D50 value 1.3 ⁇ m is used in an analogous manner with example 2.
• the product had an L value of 51.0.
• a furnace black with a specific surface area of approximately 25 m 2 /g is used in a batch according to example 2.
• Piston furnace Heating rate 950° C./hour, calcination temperature 1000° C., holding time 1 hour, oxidative recalcining at 1000° C.
• the product had an L value of 49.2.
• the product had an L value of 40.3.
• This pigment contained approximately 0.3% by weight carbon black included.
• Example 4 was repeated, whereby a reducing calcining was performed in a batch furnace at 1300° C. Dark gray colored bodies were obtained at a heating rate of 500° C./hour with a holding time of 1 hour and an oxidative recalcining treatment at 1300° C.
• zirconium oxide powders with a D50 value of 4 ⁇ m (spec. surface area 5.1 m 2 /g,) with a D50 value of 14.6 ⁇ m (spec. surface area 1.8 m 2 /g) and in an amorphous state were used.
• white products without carbon black encapsulated are obtained, since the particle size of the zirconium oxide powder used was outside of the particle size necessary for production in accordance with the invention.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Organic Chemistry (AREA)
• Pigments, Carbon Blacks, Or Wood Stains (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Silicates, Zeolites, And Molecular Sieves (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (15)

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Citations (4)

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• 1989
  • 1989-03-03 DE DE3906818A patent/DE3906818C2/de not_active Expired - Fee Related
• 1990
  • 1990-02-21 DE DE9090103318T patent/DE59001388D1/de not_active Expired - Fee Related
  • 1990-02-21 EP EP90103318A patent/EP0385247B1/de not_active Expired - Lifetime
  • 1990-02-21 ES ES90103318T patent/ES2055185T3/es not_active Expired - Lifetime
  • 1990-02-21 AT AT90103318T patent/ATE89302T1/de not_active IP Right Cessation
  • 1990-03-01 CS CS97990A patent/CS274705B2/cs unknown
  • 1990-03-02 JP JP2051587A patent/JP2848905B2/ja not_active Expired - Fee Related
  • 1990-03-02 US US07/487,295 patent/US5008223A/en not_active Expired - Lifetime
  • 1990-03-02 DD DD90338355A patent/DD292471A5/de not_active IP Right Cessation
  • 1990-03-05 BR BR909001022A patent/BR9001022A/pt not_active Application Discontinuation

Patent Citations (4)

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